I don't understand what is meant by "derive the formula for finding the volume of a sphere that uses infinitesimals but not the standard formula for the integral"? Is this talking about Gauss or what? I'm completely self taught in calculus and I did three proofs already... the old cylinder / cone proof, and the other two used the standard formula for the integral.. Even any link to something that explains this would help. I'm only aware of 7 proofs and I don't get how any of them meet both criteria..? Thanks!